APPLICATION OF INDENTATION TEST TO THE EVALUATION OF TBC YOUNG'S MODULUS

摘要

Thermal barrier coatings (TBCs) have been applied to vanes/blades of gas turbines for recent electric power stations and these contribute to the efficiency of gas turbines. Measurement of Young's modulus of the top-coat of TBCs with high accuracy is important since it is a dominant factor for determining the magnitude of thermal stress. However, until now, evaluation method for Young's modulus of the top-coat has not been established, due to difficulty of material testing in its coated form. Furthermore, a porosity of the top-coat is changed by progress of sintering phenomenon caused by long-term high temperature exposure in air, consequently Young's modulus of the top-coat is also influenced. In this study, various trials to evaluate Young's modulus of the top-coat for application of the indentation test were conducted. Firstly, both dependency of the testing load and anisotropy on calculated Young's modulus of the top-coat were discussed. Next, measurement of Young's modulus of the top-coat after long-term high temperature exposure was carried out. Obtained results were verified by comparing with other method to measure Young's modulus of the top-coat.